Marston Hefner, Claire Sinclair Marston Hefner, Claire Sinclair

Hugh Hefner's son has made headlines, but not for following in his father's footsteps.

Marston Hefner was arrested Sunday night in Los Angeles for allegedly assaulting his girlfriend, Playmate Claire Sinclair, E! Online reports.

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Police were called to the couple's home in Pasadena shortly before 11 p.m. where they found Sinclair suffering from minor injuries. Hefner, 21, was taken into custody and charged with battery. He was released later after posting $20,000 bail.

A court date has yet to be set.

On Monday, Sinclair posted a thank you to her supporters on Twitter: "There's two types of pain in the world - pain that hurts you, and pain that makes you stronger. All of your positivity is giving me strength."

Marston Hefner is one of two sons that Hugh Hefner had with second wife, 1988 Playmate of the Year Kimberley Conrad.