Not meaning to touch any nerves here (isn't that a surgeon's job?); we have all heard of a mother's instinct, something ingrained into a woman from carrying a life within her for (up to) nine months.
A father's ability to protect his child at great lengths, would be based more upon something learned, rather than an instinct based mainly upon biology.
It may not ALWAYS hold true, but, in general, it does hold true most of the time. And, yes, i DO know mothers without those instincts (or at least not very strong ones).
NEVER, EVER, was it suggested that this has to do with loving a child more or less. And it was NEVER said by me that only mothers make good parents, either. Let's not find fault by putting words in one's mouth, okay? Again, if i hit a nerve, i am sorry i did so; but i still stand behind what i wrote. And, yes, i AM a loving father of one great girl.