Is it just a case of him wanting to copy mum, my DS wanted me to paint his nails because I done mine, has to have body lotion to rub on himself because he sees me do it, had his sister put hair band in his hair cos he sees us do it, etc Likes to dress up as spiderman because sees other kids to it. Oh and when he was 2 he used to insist on taking his sister old handbag out.
My DS is 4 next month. Kids this young don't see the typical stereotype of what is girls and boys stuff/toys.
I work with various nurseries & just about every day see little boys in princess dresses, wearing tiaras etc! Even the little boys typically into cars, blocks, running around, superheroes etc....most of them go through the girly phase. See more & more boys with nail polish "like my mum has" too.