My cat who used to prefer my dad now likes my dad and I equally, and my dog that preferred my step-dad also now prefers me much more than before, though not quite equally (which makes sense since my step-dad raised him from puppyhood but I met him when he was 5). Animals definitely seen to have gender preferences.
Now that I think about it, my cat likes to put her face in my armpit now. Dunno why, its disgusting in there XD