(CBS) Keep your semen to yourself.
That's what world's largest sperm bank is telling potential donors who have red hair. The bank's director told the Danish newspaper Ekstrabladet that there simply wasn't much demand for sperm from red-headed men, the Telegraph reported.
"I do not think you chose a redhead, unless the partner - for example, the sterile male - has red hair, or because the lone woman has a preference for redheads," Ole Schou, director of Cryos International, told the Danish paper, according to the Telegraph. "And that's perhaps not so many, especially in the latter case."
Cryos, which bills itself as the world's largest network of sperm banks, has strong demand for sperm from red-headed men only from Ireland, according to Schou.
Ten percent of the Irish population has red hair, according to the website of KQED. That's compared to 2 percent to 6 percent of the U.S. population.
Schou said the bank can afford to be picky, according to the Telegraph, because it has a waiting list of 600 guys who are ready to give donation their best shot - and because the bank has reached its capacity of 70 liters of semen.
Men typically ejaculate 2 to 6 milliliters each time, according to WebMD.
What kind of donor are sperm shoppers looking for most? According to Schou, it's guys with brown hair and brown eyes. Dr. Cappy Rothman, medical director of the California Cryobank sperm bank told
Dimples? Dr. Rothman said they're a plus.