My brother masturbates in front of me bc I tease him

I (21f) am a nudist who lets my family see me naked all the time. My brother (23m) will get naked with me if our parents are gone and he is always hard AF. I've slept with all his friends and I know he is jealous and wants to have sex with me too.

Sometimes when we are naked together I will describe my sex life to him in detail and he will start masturbating right in front of me. He's probably slightly smaller than average, but it's a nice looking penis anyway. But he isn't allowed to touch me, and I don't touch him. I love teasing him and I think he loves when I watch him masturbate.

I know you won't judge us if anything happens, but I don't let him touch me bc incest is wrong. If he took control and made a move tho, I'd let him.