Legal Question in Criminal Law in California

Re: California Law

I'm not sure what you mean by "cousin by marriage". If you mean the cousin of your spouse, the answer is no. This presumes, of course, that the cousin is not also a close relative of yours, that he/she is of legal age and that the sex is consensual. The law does not require that you also have the consent of your own spouse, but secretly having an affair with his/her cousin carries obvious risks to your marriage.

The main practical reason we have laws against incest is that children born to parents who are closely related to each other often have serious medical and/or cognitive problems. That is true only of blood relatives. Marriage does not create the same risk between relatives of the married couple.

Re: California Law

I am not sure what you are asking. However, California Penal Code Section 285 defines incest as being within the degrees of consanguinity within which marriages are declared by law to be incestuous and void. There is more to the definition but it really does not apply. In the State of California one can have sex without almost anyone if they are of legal age to consent. Which means the person is 18 years or older. So no it is not illegal to have sexual relations with a cousin if your cousin was old enough to consent and you were old enough to consent. However, in California 1st cousins can not marry. I believe there are some states where it is permitted but I am not sure. However, having sex with a cousin is not illegal although it may not be advisable. Good luck