What a cute thread and I find it normal to have preferences over one gender to the next.
I must say...Most my life I have had female pets with no real reason as to why. Recently adopting Ransom my little male I will admit, I find the entire belly rubbing experience different. LOL !!
With Schatzie I just rub rub rub and even stick my mouth on her belly and blow like you would a human baby. But....well, so often now w/ Ransom I go to rub his belly and find myself saying to him, "excuse me didn't mean to violate you there!".
And most likely he will not ever get any belly kiss blows as I do Schatzie, hahahaha.
But ooohhhhh how I love my little boy!!
