Sarah Jane Nader Says It's 'Not Weird' That Brooks Was Topless In Front of Their Parents

Sarah Jane Nader doesn't think it was weird that Brooks went topless in front of their parents ... and says her sister actually gave some good advice about getting intimate with her 'DWTS' co-stars.

We caught up with Sarah Jane in NYC Wednesday ... and she had a message for everyone who criticized how her sister had her boobs hanging out in front of their parents.

The way Sarah sees it, it's only weird if other people make it weird ... and she says the haters are the ones making it weird.

She also says that when it comes to hooking up with her "Dancing with the Stars" partner ... to learn from her mistakes.

Peep the clip to hear how Sarah Jane tells it!