Greetings! Thanks for the query.
The growth of beard is dictated by many factors including genetic programming, hormones (
testosterone), ethnicity and nutrition.
Checking the testosterone levels will suggest if there is any hormone deficiency. If father has good beard does not mean every male person in the family will have the same (though the chances are more).
If beard growth is not due to hormone deficiency then you need to consider transplantation of scalp hair to beard area if you are desperate for full face beard. You need to consult highly skilled Hair transplant surgeon to discuss this option.
Minoxidil lotion (used for scalp baldness) is not licenced for beard growth.