By Sandra Rose  | 

BACKGRID

A DNA test has removed all doubt that Tristan Thompson is the father of Houston fitness trainer Maralee Nichols' baby boy.

Tristan immediately took responsibility for his promiscuous behavior after receiving the test results.

In an Instagram post, he confirmed he fathered the boy -- born on December 1.

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"Today paternity test results reveal that I fathered a child with Maralee Nichols," he wrote. The 30-year-old NBA star apologized to his long-suffering baby mama, Khloe Kardashian, 37.

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"You don't deserve this," he told Khloe, who looked unbothered as she left a Kardashian family Christmas photo shoot last month.

"Today paternity test results reveal that I fathered a child with Maralee Nichols. I take full responsibility for my actions.

"Now that paternity has been established, I look forward to amicably raising our son. I sincerely apologize to everyone I've hurt or disappointed throughout this ordeal both publicly and privately."

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Tristan is the father of Khloe's only child, a 3-year-old daughter named True Thompson. Khloe is pictured leaving her daughter's dance class with BFF Malika Haqq and her son, Ace.

Nichols, 31, filed for child support after moving from Houston to California, where she gave birth.

Her attorney felt vindicated. "There was never any doubt that Tristan Thompson was the father of Maralee Nichols' baby," attorney Harvey Englander told DailyMail.com in a statement.

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"Tristan made numerous false and defamatory statements and declarations about Maralee over the past few months, and she is taking his contrite statement today in the context of all of those statements."

The baby makes three children by three women for the promiscuous athlete. Tristan fathered a son, Prince, with his ex-girlfriend and Instagram model, Jordan Craig, in 2016.