Yes, it's difficult to persuade people used to a way of thinking to replace that way of thinking. The thing to do for the moment is to continue to invest yourself and be silent as you make a profit and to reinvest that profit until you get a sizable amount and then surprise your parents. Don't miss out on opportunities because your family is not interested. Time will make your father change his mind.
I wouldn't like it very much if my parents invested in alt coins unless they are rich and can carry the burden of losing everything. Making decisions for others especially when money is involved is complicated in my opinion. Losses feel much harder than if it is your own money. Of course you are happy when they can make some nice gains, but if that doesn't happen it feels awkward.