I'm going to use a comparison. When choosing a pet rat, for example, you look at the pups squirming in the box, all running around. Pick a few up. The calm ones are the male rats, while the female rats don't stop squirming. They explore, and take a little longer to trust their beholder. Male rats on the other hand, when you first hold one, that is not familiar with you, will sit in your hand for a minute and look at you, feel you beneath his feet. He trusts instinctively. Male rats are also somewhat lazier. One could debate whether it is trust or laziness that makes a male rat a calmer pet. But Rats are like any other animal. Their behavior related to a dog's, they are equal companions and just as intelligent. I am not going to even bother with organs. But as animals are in nature, humans are much the same. Whether or not you choose a male/female rat does not matter, you will be happy with whichever you choose, because you can train any pup from young age. Its called adaptation. For this reason, humans remain close to nature because we, as nature intended adapt to our surroundings. Whether or not it is a male or a female, does not particularly matter.