God has warned us in the Bible. The Bible consists of so many warnings from God about the things that we should do and the ones we should not. Thou shalt not get married to a close relative. God said that we should never uncover our mother or father’s nakedness for it is a sin.
Some people actually prefer to listen to their country’s rule of law instead of that of God. Some countries legalize family members getting married to each other but God doesn’t want it so we should not do it. It is prohibited to marry or have sexual relationships with your family members.
https://youtu.be/R_GVqSdYWUU?si=vCOav4IIuPhLTRie
Leviticus 18:6 tells us that; “None of you shall approach to any that is near of kin to him, to uncover their nakedness: I am the LORD.”
This is the statement God made to us so, we should follow it. There are many fishes in the ocean. There are so many people available for us to follow or get married to instead of deciding to get married to our siblings, parents or cousins.
Love your family members but not to the point of wanting them sexually. It is bad and not accepted by our Lord.