Knowing Morgyn, they probably started out as a biologically female non-binary. Then, when they became more powerful and confident, they transisitioned. BUT contrary to common belief I do not think that Morgyn went FtM. It's more in-character for them to get rid of everything and become as androgynous as possible (just don't ask me what exactly they have beneath their skirt. I only know it's neither a man's nor a woman's equipment).
In my game I went with a simpler lore and made my Morgyn biologically male, reasoning that as a non-binary they just do not care what they are biologically. For outfits, facial hair and makeup I chose a mixture of male and female.