I'm the only one in my family with an upward palpebral slant. No down syndrome & no known diseases or illnesses. My fathers side doesn't have it and my mother doesn't, unsure of her family because she is adopted. Is this a hidden gene from my mothers side that didn't show up in her? How would I find out what causes this? I've always been asked if I am Asian and no one else has my eyes in my family.