I want to breed these two but I'm not sure which one to change to male or if it makes much of a difference

https://www.sylestia.com/view/pets/?petid=6902193
https://www.sylestia.com/view/pets/?petid=6902207

Well, the choice is yours! You can change whichever one to male that you choose.

Does the gender affect which traits are more likely to pass on to offspring?

No the gender doesn't affect traits! So whichever one you change will have an equal chance of passing down traits :)

All offspring of those two if paired would have the exact same trait outcome, regardless of which was male and which was female, since gender doesn't affect trait inheritance. Sylestia uses punnett square genetics, so given the traits these two have, all offspring of these two would be;

G1 - Carried Clouded Hearts
G2 - Nothing
G3 - Nothing
M1 - Visible Enchanted Butterflies with Hidden Lovely Hearts
M2 - Carried Twisted Root Armor
M3 - Carried Feathered Cherub Wings



I think most people if presented with this would probably swap the 3v, since male sylesti don't have a breeding cooldown and can thus be paired with multiple females at once?