What causes men to have a fem. voice?

In the last year I've decided that I was tired of being single and that I wanted to get back out into the dating scene. I did meet one pretty amazing guy in Oct. of 2010, but that ended up just turning into friends. Then I recently met an extremely sweet guy over an internet dating site that someone referred me too. The trouble is that both of these guys had a similar chararteristic. Very feminine/soft spoken voices. The first guys wasn't that bad, but the new guy that I actually like..I can't seem to get past his voice. I mean if you know or remember how Michael Jackson spoke, this is basically how soft spoken the new guy is. I feel like his voice is more feminine than my own. It's not really enough to scare me away from him because I know he's a great catch..but I am afraid that he's gonna have issues with my family eventually. I know how my 2 older brothers and father can be. They're all very masculine and have deep voices and I know they're gonna try and convince me that he's gay. I know that he's not. I guess my question is, what causes this in some men?? Are there any other women out there dating a man with a really feminine voice?? I feel really bad/shallow for even being worried about what my family might say..but it wouldn't stop me from seeing him. Just cause me to keep him from my family to protect him. What do you think?