This Father's Day it's nice to remember that dads are pretty important to learning the ropes when it comes to love and relationships, especially for boys. I'd say that if you compare dad's presence, when it comes to love stuff, with a NASA rocket that dad's presence, when it comes to love stuff, is way more important.
Dudes who grow up without a dad (or at least an active, positive male role model, like a Bernie Mac character) are at a serious disadvantage when it comes to romance. While some of 'em figure it out, lots are mama's boys, resentful of women or, weirdly, both (think Norman Bates but generally less violent or likely to cross-dress).
Dads who care, even really cool dads who let you drink beer, provide a grounding and safety. Per MSNBC, involved dads curb risky teen sex (unprotected sex, not necessarily anything pertaining to fire or chainsaws) at about twice the rate of involved moms. Maybe "involved dads" are intimidating to teen Don Julios [sic]. Maybe they reluctantly buy condoms or birth control because they know their kids are way past heavy petting with their boyfs / girlfs (they maybe even be rounding third and heading home as we speak).
While NO ONE enjoys discussing the nuts and bolts (double entendre!) of sex with any family member (save sage older, same-gender siblings), dads are sometimes a great source of advice on making night moves. Alec Baldwin's character in Outside Providence tells his moron son, "Making sex is like Chinese dinner, it ain't over 'til you both get your cookies." Wonderful. Em & Lo put together a fantastic list of accidental sex advice that people get from dad (God, do I agree with their sentiment about passing gas as mixed-company humor).