Jason Collins and his brother Jarron are identical in every way, same height, same smile, same DNA. The brothers have even followed the same path in life, playing in the NBA.
And yet, Jason is gay and Jarron is straight. He's married with three kids. Jarron says he had no idea his brother was gay until last year.
George Stephanopoulos asked, “Your twin brother Jarron, he didn't know. How is that possible?”
Jason said, "I’m really good at playing it straight.”
So how is it that twins can grow up together and have the same experiences, but one is gay and one is straight?
Scientists believe it is the strongest evidence yet that homosexuality is genetic rather than learned behavior.
INSIDE EDITION asked TV’s Dr. Phil for his take.
"A lot of people might say, 'they are identical, wouldn't they be the same?' Not true. Frankly, I don't think environment has anything to do with it," said Dr. Phil.
Like the Collins brothers, Tommy and Tanis Reinert are identical in every way but one, Tommy is gay and Tanis is straight.
Tommy said, "It was really difficult for me, I just wanted to be normal, in a sense. Back then that is how I looked at it. I struggled a lot with it, and that is why I didn't tell anyone, I just sort of kept it to myself."
The brothers are professional models. They’ve been inseparable since birth, Tanis says he always knew his brother was different.
Tanis said, "I always suspected he was gay because he always listened to girlie music."
No one is being more supportive to Jason Collins than his twin brother. Here’s what he wrote in Sports Illustrated, “He’s my brother, he's a great guy, and I want him to be happy. I'll love him and I’ll support him and, if necessary, I’ll protect him."
Dr. Phil said, "That has got to mean everything in the world. There is a special connection there."
We caught up with Dr. Phil as he was promoting his interview with a woman who claims her boyfriend abuses her daily. He denies it. She confronts him on Tuesday's Dr. Phil.