As far as I know, humans will mate with just about anything that looks remotely human, and sometimes with things that don't.
LOL...
And humans aren't the only ones that have that problem.
Apparently the fallen extraterrestrial angels had that problem too.
"And it came to pass, when men began to multiply on the face of the earth, and daughters were born unto them, That the sons of God saw the daughters of men that they were fair; and they took them wives of all which they chose." -- Genesis 6:1-2
"...and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown." -- Genesis 6:4
"... they shall mingle themselves with the seed of men ...." -- Daniel 2:43
"And it came to pass when the children of men had multiplied that in those days were born unto them beautiful and comely daughters. And the angels, the children of the heaven, saw and lusted after them, and said to one another: 'Come, let us choose us wives from among the children of men and beget us children.' And Semjaza, who was their leader, said unto them: 'I fear ye will not indeed agree to do this deed, and I alone shall have to pay the penalty of a great sin.' And they all answered him and said: 'Let us all swear an oath, and all bind ourselves by mutual imprecations not to abandon this plan but to do this thing.' Then sware they all together and bound themselves by mutual imprecations upon it. And they were in all two hundred; who descended in the days of Jared on the summit of Mount Hermon, and they called it Mount Hermon, because they had sworn and bound themselves by mutual imprecations upon it. And these are the names of their leaders: Semiazaz, their leader, Arakiba, Rameel, Kokabiel, Tamiel, Ramiel, Danel, Ezeqeel, Baraqijal, Asael, Armaros, Batarel, Ananel, Zaqiel, Samsapeel, Satarel, Turel, Jomjael, Sariel. These are their chiefs of tens." -- Enoch 6:1-8
"And all the others together with them took unto them wives, and each chose for himself one, and they began to go in unto them and to defile themselves with them, and they taught men charms and enchantments, and the cutting of roots, and made them acquainted with plants. And they became pregnant, and they bare great giants, whose height was three thousand ells: Who consumed all the acquisitions of men. And when men could no longer sustain them, the giants turned against them and devoured mankind. And they began to sin against birds, and beasts, and reptiles, and fish, and to devour one another's flesh, and drink the blood. Then the earth laid accusation against the lawless ones." -- Enoch 7:1-6
"And in the twelfth jubilee in the seventh week thereof, he [Enoch] took to himself a wife, and her name was Edna, the daughter of Danel, the daughter of his father's brother, and in the sixth year in this week she bare him a son and he called his name Methuselah. And he was moreover with the angels of God these six jubilees of years, and they showed him everything which is on the earth and in the heavens, the rule of the sun, and he wrote down everything. And he testified to the Watchers, who had sinned with the daughters of men; for these had begun to unite themselves, so as to be defiled with the daughters of men and Enoch testified against (them) all." -- Jubilees 4:20-23
