That’s kind of hard to say. The effect of having poor parenting from either a mother or a father show up later in life. The effect of good parenting on either end shows up later in life. When the kids go wrong, the blame on the parents can go either way, although it does seem to depend on the category of sin the child gets into.
I guess, though, as Bill Cosby pointed out, a father can coach his kid through thick and thin, and the kid gets into the end zone, and he mugs to the camera: HI, MOM!! Mothers get the opportunity for an attachment that shows up in the most oft-seen religious art in the world: the madonna and child. St. Joseph and the child Jesus just don’t carry the same primal punch.
Yes, dads never make up those nine months and the physical bonding. If we didn’t have that, we imagine we could have. I’m sure a social scientist or psychologist could go on and on, but moms have the edge in popularity, it comes from a profound place, and I don’t think that will change.