Of course the foreskin would grow in any situation. Puberty is biological programming for all the cells of your body. In addition to its pubertal growth, it would expand in size as necessary to accommodate the overall penis increase in size, for example if it is regularly retracted and being forced wider by a widening penis. It is also worth noting that the commencement of teenage puberty proper with commenced sexual identity, functionality and context in mind and body, is the natural commencement of manhood / natural young adulthood. There is a great deal of flawed and false social arbitrary infantilization occurring which really originated in the late 19th early 20th centuries but which over the past century have propagated increasingly outrageous, destructive, infantilization insults towards teenaged young people. Nature does not require all developmental potential to be complete prior to obtaining natural young adult identity...Most men do not develop their full potential of chest or facial hair until they are well into their thirties, but we don't say, hey you're only 29 so you're not an adult. Nature doesn't work that way. Likewise the notion of adulthood occurring at an instantaneous moment in time when an individual instantly morphs into a different individual is just absurd to unhinged levels, yet this misrepresentation of identity forms the basis of infantilization discrimination against a marginalized group of society - teenagers - and in doing so, a great resource is lost, as they are in truth by and large remarkably competent when given the opportunity. Sorry for the lecture, it's a topic I'm passionate about. I work with many teenagers and know their competencies. I also previously studied philosophy and justice studies. Back to the point at hand, the foreskin will grow in any case.