<p>That's not true at all. You can't just go by the % of private school students, because many of those are actually from urban parochial schools that draw mostly disadvantaged students, and also because even at the "prep" or "boarding" schools themselves, many of the students these days are on financial aid and do not come from the typical background you would associate with such high schools. Your best bet if you want to see how "preppy" a place is is to visit for a few days, including a weekend evening and a weekday, and sample the social life for yourself.</p>