Thank you this is was I thought too.
I think the area where is testicles will be (he's only 10wks old) was mistaken as the vaginal opening as it does look like that. His penis was well hidden in his fluffiness.
And his mum was a tortie, he's mainly black with the brown on the tips of his fur.
Thanks everyone, still can't get the perfect photo here is the last attempt, and we have no idea what to call the kitten, as we had a girlie name and if he is a boy it's not really suitable for him.
Kitten is also fluffy too so that makes it difficult in these pictures it makes me think boy. I've added kittens cute face too so it's not all backside.