<p>There are locks on all the bedrooms of our house (which can easily be opened from the outside with a screwdriver if needed). I would be unhappy if either of my unmarried kids locked me out of the room which they occupied with someone else. </p>
<p>It’s my house, my rules. It’s pretty moot at this time, since neither kid has ever locked the door while someone else was in their bedroom.</p>
<p>Your brother should never have barged in without being given permission to enter. A closed door means that one should knock and get permission before entering.</p>