There are so many things that need to be said here. First, you list your age as 20 years old, which means that there needs to be an adult conversation around this. I’m being clear about the age in my response because it would be a very different response if you were 10 or 13 years of age. In those instances, I would encourage you to have support before you begin to deal with this. I am assuming your sisters are younger and this means that you will have to take the lead in speaking up, standing up, and getting them support to stop him.
Whatever his reasons for this the fact that it feels invasive, uncomfortable, and inappropriate is enough to demand it stops. Your father’s attachment needs are not your concern — but the emotional well-being of you and your siblings is.
The fact that your father hasn’t gotten the message and continues to be inappropriate with you is a deep cause for concern. The reality that your mother doesn’t take this seriously is just as damaging.
I wouldn’t mince words with this. I would talk to your sisters, make an appointment with a family therapist (you can check out the Find Help tab at the top of this page or check this group for qualified people) and then let your parents know that you’d like them to come. While it would be good for everyone to talk about this issue with a professional present, be clear that you are going to go whether or not your parents or siblings attend.
This strategy will do several things. Hopefully, this will wake your parents up to the fact this isn’t normal and needs to stop. Secondly, it lets your siblings know that you want to help and empower them. Finally, if you end up going alone, you’ll have the support of a knowledgable professional that can help you deal with this inappropriate situation at home.
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral