Sex comments from older brother?

I like this 19 year old guy named Bob. He drinks sometimes and is somewhat social. He is also athletic. He plays basketball and baseball. He is also family oriented. He has 5 siblings. He has an older sister, an older brother, and 3 younger brothers, ages 14, 11, and 10.
His 11 year old brother Jim told me a couple of weeks ago that his best friend is Bob. But Jim can be a little wild. I have witnessed him look through a Kohls magazine and judge the models and their boobs on the bra page, he tells my brother(jokingly, I hope) to never love a woman(or fall in love), and he makes sexual comments sometimes.
I know that Jim is only 11 years old, but do you think that he could have gotten this stuff from Bob? Jim could have gotten this from his other older brother that is 14, who could be going through his horny stage, but I'm still worried.
Bob has never had a girlfriend, but he wants friendsship and dating, according to facebook, and apparently last year he used to like this girl, but she had a boyfriend.