In 1997, Kyle's mother, Diane Jenkins returned to Genoa City a well-respected architect. Victor Newman romanced Diane, and Diane and Victor were married. Diane decided she wanted a baby, so Victor countered that notion by having a vasectomy behind her back, but he had made a deposit at a sperm bank prior to the procedure. Diane was furious when she found out about the vasectomy. Then Victor's ex-wife Nikki was shot and Victor arranged with Diane for a quickie divorce so that he was free to remarry Nikki on her deathbed, so Nikki could die happy. The plan was for Diane and Victor to remarry after Nikki's death. But Nikki lived, and Nikki and Victor stayed married.
Diane intercepted Victor's notice from Robertson Labs saying the renewal time was due on his sperm deposit. Diane decided to steal the sample to become pregnant with the baby he had deprived her. Diane, posing as "Mrs. Victor Newman," showed up at the lab and arranged to have the deposit delivered to her penthouse where she kept it in a freezer in the closet of a locked room. But the deposit was stolen.
About a month later, Diane intercepted another letter stating, to her shock, that the sperm sample had been returned to the lab. She quickly went to a doctor, and she was artificially inseminated using the sample from the lab. After the baby's birth, she told Victor that the boy was his, and he insisted on DNA tests. Diane was shocked to learn the test showed her baby, Christian Victor Newman, was not Victor's child after all. Diane left town with her baby.
It was later disclosed that Nikki, with the help of Jack, had employed a detective's operative to get into Robertson Labs and switch the sperm samples to thwart Diane. But Nikki's attempt to help Victor resulted in Jack being the father when the man grabbed Jack's deposit as the nearest sample to replace Victor's. Diane returned to Genoa City with her baby, renamed Kyle Jenkins after Diane's father, with his nurse, Graziella. Jack then found out that his stored sperm had fathered Kyle.
Diane and Kyle moved into the Abbott pool house so that Jack could share custody. Then the Abbott pool house burned down and the police called it arson. Jack and Phyllis used the knowledge that Diane had done it as blackmail to get Diane to turn over custody of Kyle. But due to the friction between Jack and Phyllis, Jack eventually gave Kyle back to Diane. Diane moved to Chicago, taking Kyle with her.
In February 2010, Jack's new wife, Emily, asked Diane to return to Genoa City with Jack's son, Kyle, for a visit. After a short confrontation with Phyllis, Diane and Kyle returned to Toronto, Canada, where they lived.
In October 2010, just as Jack and Phyllis were celebrating their reuniting, the Abbott manor doorbell rang, and there stood Diane. Diane claimed to want Jack to get to know his son. Diane enrolled Kyle in school and gave life in Genoa City another try. While they lived in Toronto, Kyle had become quite the hockey-player, and he spent a lot of his time playing.
When Phyllis heard that her enemy Diane was staying in town and accepting a job with McCall Unlimited, Phyllis posted a story on the Restless Style website exposing all the dirt on Diane. Once Tucker saw the story, especially that Diane was not a partner in the company she worked for in Toronto, he rescinded his job offer. Later Diane attacked Phyllis for the article and Jack for apparently condoning it, and Diane told Jack he would never see his son again. While Diane was out of town, desperately looking for work, Kyle read the article, ditched his baby-sitter and confronted Jack and Phyllis, demanding to know if his mother had really done all the things in the article. Jack ended up breaking it off with Phyllis while he mended his relationship with his son and Diane. When Jack found a past-due notice for Diane’s room at the Athletic Club, he paid it for her until the end of the year, and also Kyle's tuition to Walnut Grove Academy.
Diane accepted a job at Newman and Victor's invitation for her and Kyle to move into the carriage house. Diane and Victor became lovers again, then she and Kyle moved into the ranch house with him. Victor began showering Kyle with hockey equipment, game tickets, and other gifts, and Kyle played hockey on the pond at the ranch. When Jack returned to town and discovered that Diane was now living with Victor, he insisted that Kyle live with him. After Diane got her son's blessing, Diane and Victor flew to Las Vegas, and were married. Phyllis and Jack later reluctantly dropped off Kyle to live at the ranch. But Victor fell back in love with Nikki again and told Diane he was getting an annulment. Being jobless again with nowhere to live, Diane got Jack to take Kyle to live with him.
Looking for revenge, Diane made a deal with Adam Newman to frame Victor for Diane's murder. She convinced Victor to sign papers to become Kyle's legal guardian as part of the setup. Adam gave Diane cash and forged identity papers in the names of Jennifer and Timothy Bilton. Diane sent Kyle to boarding school in Switzerland as Timothy, telling him not to contact anyone, and that she would be joining him soon. Jack confronted Diane about secreting their son away. Diane offered to hook up with Jack again to give Kyle a family, but Jack refused, so Diane told him that he would never see his son again.
Diane's body was found dead, floating face down in the stream in the park. Her diary disclosed that she was hated by so many that there were several suspects. Unable to contact his mother, Kyle phoned Jack from Switzerland but hung up, so Victor, Michael, Paul, and the police cooperated together to help locate him. He was finally identified by tracking children who traveled alone, and Jack went to Switzerland, told Kyle of his mother's death, and brought him home. Jack was livid when immediately upon their arrival, Victor handed him the papers giving him legal guardianship. Jack tore up the papers and vowed to fight it.
It took a full year to solve the case that a drunken Nikki had killed Diane in self-defense, then had blacked out, not remembering. Victor never laid claim to Kyle, and he stayed on living with Jack. After Christmas, Kyle begged Jack to attend high school at Northwood in Lake Placid, NY, accepting a once-in-a-lifetime offer to join their hockey program.
When Kyle Abbott returned to Genoa City in his early twenties, Kyle hooked up with Michael Baldwin's half-sister, Eden. Kyle became resentful when he discovered that his father Jack was romantically involved with Nikki Newman, the woman who had killed Kyle's mother. Kyle moved into the Newman Ranch and Victor gave him a job. Nikki then called off her affair with Jack for Kyle's sake. But after Abby had a heart to heart with Kyle, he apologized for being a jerk, telling Jack that he wanted him to be happy, and if Nikki made him happy, Kyle would have to get over it. So Jack declared his love to Nikki, and asked her to marry him again. Jack and Nikki were married a few months later, with Kyle refusing to attend the ceremony.
When Abby was arrested for pulling another publicity stunt where she led everyone to believe that she had been kidnapped, both they Abbots and Newmans washed their hands of her. Abby got off by paying a $100,000 fine, and only Kyle was there to pick up her when she was released. Kyle cheered her up by showing her the front page headline "Naked Heiress Kidnapping Hoax".
After Nikki left Jack the day after their wedding to hunt for the missing Victor, Kyle began helping Jack to walk again, and when Sharon turned into "queen of the manor" after Victor's disappearance and became CEO of Newman, Kyle quit his job at Newman, and moved out of the ranch and back into Abbott Manor with his father. A couple of months later it was mentioned that Kyle was working an internship in New York City on Wall Street. Kyle returned home after spending Thanksgiving with Traci and Ashley, and went back to work at Newman working for Jack who had become CEO.
Concerned that he would lose the only parent he had left, Kyle leaked to the press that Jack had become addicted to pain killers. But when that did not stop Jack from over-medicating, Kyle got Phyllis, Billy, and former alcoholic Neil to help stage an intervention. But Jack claimed they had insulted him, fired them all, and threw them out of his house. As Jack fought to get off the drugs, he realized that he had forgotten Kyle's birthday, and gave him a compass which he treasured that his father John had given him, passing on the hope that Kyle would always "know his true north."
Once Jack was himself again, he realized that he belonged at Jabot, not Newman, and left Newman in Adam's hands. When putting together his team to run Jabot, Jack hired Billy and Kyle, and Neil was made head of the new fashion division with Cane and Lily under him. A few months later, Abby returned to Genoa City and convinced Jack that she had finally grown up and to work for him at Jabot.
Abby warned Kyle that Summer Newman had crush on him, but he wouldn't believe it. Meanwhile Summer wrangled a job as an intern at Jabot working with Jack to be close to Kyle, and pumped Jack for information on Kyle. Unable to get Kyle to pay attention to her, Summer arranged for him to walk in on her without her blouse, claiming that she had spilled coffee on it. Kyle was mortified and tried to turn away, finally giving her his jacket to cover herself – just as Phyllis walked in on them. Phyllis saw through Summer's ruse and sent Kyle away. Phyllis told Summer that she wanted her first time to be special, that Kyle had no feelings for Summer, and she would only get hurt. Phyllis asked Summer, "How many times have you said you did not want to be like me?" and told her to back off.
Kyle walked out of his shower to find Summer naked in his bed. He asked her to get dressed, and told her he thought of her as family, as the little girl with her dolls. When Summer was not dissuaded, Kyle told her he was involved with someone else, and that she was too young. So Summer's friend Courtney gave her a makeover to show him she was no longer a kid. Kyle did a double-take when he saw Summer, but still told her no. But when Phyllis agreed to move in with Jack, Summer talked her mother into letting her move in with them too, so that she could live under the same roof as Kyle.
After Nick overheard Summer confiding in Avery about wanting Kyle to be her first sexual experience, he went ballistic on Kyle. As Summer told her mother how Nick over-reacts to the very idea of her and Kyle, Nick pulled Summer's paternity results from a locked box, showing viewers that it had been marked "cannot be verified" due to a damaged sample. Nick explained over Cassie's grave that he had lied about the results because he feared losing another daughter. But after Kyle and Summer appeared to be getting closer, Nick arranged a paternity test.
Summer accepted a prom date from Fen, but ditched the prom, dragging Fen to a party she had set up at her mother's penthouse instead. Everyone was drinking, and they played truth or dare. As a tipsy Fen completed his dare to kiss Summer, Kyle burst in to rescue Summer after receiving a text. Phyllis, who had just moved out of Jack's, arrived at the penthouse to find Kyle punching Fen in the mouth. She sent the other kids home and called Nick, Michael, and Lauren. Afterward, Nick arranged a paternity test.
Kyle asked Summer to dinner, and they kissed good night when he took her home afterward. Following Summer's high school graduation, she and Kyle went to dinner at the athletic club, and Summer suggested they get a room. Kyle talked her out of it, saying they were rushing things. Phyllis left to attend a focus group on eyeliner in Chicago, taking Kyle with her to keep them apart. Phyllis came on to Kyle, and after one kiss, Kyle called things off with Summer. The next day, Summer said goodbye to Faith, texted Kyle, and ran away to Chicago. When Kyle realized how much he had hurt Summer, he called her and apologized, asking her to return, and they would be together again.
Back in Genoa City, Kyle arranged to get Billy's club after hours, invited Summer, and gave her an armload of yellow roses, begging her to start over. Summer had to be the one to tearfully tell Kyle that she had found out that Jack was her real father which meant that they were brother and sister. Kyle walked out upset, unable to deal with it.
Jack and Jill were putting their heads together to come up with a way to get Chancellor-Newman away from Victor. Pulling in Devon, Kyle, Cane, Neil, and Jack's new assistant Hilary, they decided they needed a mole to work from the inside. Kyle volunteered for the job, but Jack turned him down, saying that unlike Victor, he would not use his kids to fight his battles for him. But while Hilary and Jack were going through a list of Chancellor-Newman employees for a possible candidate, Kyle was asking Victor for a job, telling him that he was tired of being Jack Abbott's son, wanted to be his own man, and to make a name for himself. Victor hired him but told him he had to cut his long hair, gave him full security access, then Victor had someone watch his every move. Victor began pitting Kyle against his grandson Noah, asking the two of them to present their ideas in front of each other, and choosing Kyle's over Noah's. But Abby talked them into working together instead.
Jill told Jack about a cancer drug research company that Chancellor had acquired while she was working there called Bonaventure Industries, and her suspicions that they were cutting corners trying to stop their losses. Jill pointed out that if they could prove it was an unethical subsidiary, it would create bad publicity with the FDA for Newman-Chancellor. Kyle offered to get more information on it, but Noah caught Kyle in Victor's office after Kyle had just photographed the file. Victor arrived and caught them fighting, then assigned both of them to the Bonaventure company to find out more about it. Noah returned and told Victor that he had caught Kyle in his office and suspected he was spying on Victor. Kyle disappeared from town with no explanation, but was referred to often as being in touch with Abby and Jack. At Christmas 2014, Kyle was said to be in Italy skiing with friends.
Kyle reappeared in Genoa City on Valentines Day 2015 when he was found trapped in a ravine near the Abbott cabin. He claimed that he had been on the way to Abby's party at the cabin, but later recalled peeping in the cabin windows and seeing the party-goers passed out inside. Kevin, Mariah, and Noah discovered a bloody towel hanging out of the trunk of Kyle's car, but Kyle said that he had had a bloody nose. Later that night, police broke the news to Summer that they had found Austin dead behind the wheel of a wrecked car, and Summer identified the body in the morgue.
Victor welcomed Kyle home, saying that he had heard great things about his work in New York City, and that Kyle's past spying on Victor had been forgiven.
Noah, Abby, Kyle, Mariah and Kevin comforted Summer as she watched Austin's videos on his laptop. One was of Austin telling Summer that rather than roses and candy Valentines, he needed to give her an apology. Saying that he did not like himself much lately, there was something she needed to know. But he never finished, as Summer had interrupted him. Abby left, and Kyle followed her to Crimson Lights. He told her that he had been in town a while and had been following them around, that he had confronted Austin about their affair, and they had fought. Abby begged him not to tell Summer.
During Austin's memorial service, Summer suddenly remembered an argument she had witnessed while drugged that night at the cabin. Austin and Abby were admitting they were having an affair. After Summer thanked everyone for giving Austin a second chance, she glared at Abby and shouted, "YOU slept with my husband!" All eyes turned to Abby, who was mortified and ran out.
Summer and her friends returned to the cabin following Austin's memorial service, and the armoire was opened to reveal "I know what happened here" written in lipstick on the mirror inside. Kyle told how he had returned to town, and after seeing them together, confronted Austin. They fought, and Kyle threw Austin a towel to wipe up his blood. After Austin's death, the bloody towel was found in Kyle's trunk by Kevin, Mariah, and Noah, and the DNA matched Austin's. Later after Kyle discovered that Sharon Newman had a motive to kill Austin, he wrote "I know the truth and so do you." in lipstick on her living room mirror, hoping she would crack.
Kyle tried to comfort Summer, telling her that she was the reason he had returned to town, that he wanted to be her protector to keep her from getting hurt again. Kyle kissed Summer, telling her that he needed her in his life.
After viewing some of the deleted videos which Kevin had found and unencrypted on Austin's laptop, they began to believe that someone had killed Austin to keep their interview from being made public. When Courtney did not show up at the wedding, the young people all received a mysterious text asking them to meet her at the Abbott cabin. The group found Courtney dead in her wedding gown in the armoire at the cabin. A note in her hand said, "I warned you. Stop digging." The police showed up, and the group had to admit Austin had been murdered to explain Courtney's. Paul interviewed each and was appalled that none had come forward about Austin's murder, but understood that they had been threatened. No one in the group was arrested, but were told to keep their mouths shut, so the murderer would assume the police still thought Austin's death had been an accident. Paul warned them not to mention the connection to Courtney or one of them could be next. Kyle tipped Paul to Sharon's interview with Austin where she had told a Newman family secret.
Kyle escorted Summer to the benefit honoring her aunt Avery at the GCAC, then took her home where they made love for the first time. Noah walked in on them, looking for Summer to commiserate over Courtney. He left, upset with their behavior.
Kyle arranged a private dinner date, renting the GCAC rooftop deck with dinner prepared by a TV chef, hired a well-known singer/piano player, and gave Summer a diamond necklace. But Summer reacted by accusing Kyle of having changed, and not liking it. Summer explained that they had both come from money, but they had never been about the money, and walked out.