Interesting. In straight porn, moms (or MILF) is a huge niche, but you can get your site disqualified in linklists if you use "mommy" instead of mom. It was explained to me that "mommy" is the word a child would use when talking to his own mom, and therefore carries incest connotations. Mom is apparently a broader term, as in saying someone is a "hot mom". I gather from this thread that you don't have that distinction in gay porn and that daddy is actually preferable to dad or DILF?