I know I've read about this, and to make sure I didn't bias the result I've just run the test without checking what the answers should be.
I took a nail, hung it on bit of string and went and held it over Destiny, and it swung in circles, Appy Gilmore, no swinging at all, good job, he's a gelding
Ace definite backwards and forward swing, Alto, no movement at all, once again good job seeing he is baby daddy to one of the foals.
Now then which way round is which?, a quick google search shows both answers for both sexes:roll:
If I was put in a corner and hit until I admitted it, I would love Ace to have a filly, Destiny, mmm not so worried.