I am unsure whether or not you know why you and your cousin are attracted to each other, so let me share with you some brief information. The sexual imprint age of an individual is from birth to approximately six years old which desensitizes siblings (and other family members) belonging to the same household from becoming sexually attracted to each other. You and your cousin grew up in two separate households, skipping the age of learning: "he is my blood relative, therefore, we shouldn't mix our genetics". Then, his coming of age being: old enough to legally seek his biological family, he sees you and feels a connection far from just love for a family member. Same goes for you as well! When this happens, it's called: genetic sexual attraction (GSA). That said, you can't control who you fall in love with. Before you two met, you were just strangers and now, you're very great friends (and cousins) who share a lot in common and equally hope for a harmonious union. It really is no fun having someone so amazing that you can't share with the world. How are your friends handling the news? Your friends (and his friends) are family too. For your family, I recommend waiting because over time, it will sink in for them. You can educate your family regarding how safe it is to be together with your cousin (if you haven't already). You can guide them to this website. But as the saying goes: You can lead a horse to water, but you can't make them drink. Or: You can lead a human to knowledge, but you can't make them think. To elaborate, every human has something called: schemas. It's how we make sense of our surroundings and categorize everything as a survival technique. Your father, for example, sees you as his daughter. You are his offspring and he wants his lineage to survive. Then your cousin comes into the picture and your father's vision of his daughter marrying a healthy fellow becomes skewed because your cousin is family. Subconsciously he thinks: blood is being mixed, and that blood isn't 'fresh' or 'new'. As for actually telling your family, the choice is yours. I recommend waiting since your boyfriend does seem very reluctant at this time. You are also both young because at 18, there's still a transitioning stage from teen to adult. I'm sure your parents see this as well and they want to protect you. Your life and your decisions are yours alone! Me giving you advice (or anyone else here) is similar to your family. You can listen, but what you actually do is your choice, not mine or theirs. Nobody can force you or keep you from doing what you love or from being with who you love.