Can I do real push-ups or do I have to do "girl push-ups"?

I do kickboxing/muscle training once a week. I've only been doing it for like two months, but my teacher (who is a man) makes us do push-ups. I only do about seven without stopping. But my p.e teacher (who is a woman) said that girls shouldn't do real push-ups. You're meant to do it leaning on your knees or something because it damages your ovaries or something. I was just wondering do I have to do "girl push-ups" or can I do real push-ups? And should I tell my kickboxing teacher that we(it's an all-girl cl) can't do push-ups? (Oh and I'm 13)