Like say if someone, as a result of their mental issues, engaged in behaviors that were isolating, coercive, etc. Are there people like that who are just too mentally ill to change those habits in relationships even with outside help?

Realistically how would you get away with killing someone that has no ties to you

About seven inches tall, could they do it?

So say hypothetically you have a sibling, you both are adults and mentally sound and well off. They're any gender you want and look like your dream person and act like your dream person and they consented to incest would you have sex or date them?

Like in animals not in humans btw