There are two "tell me about yourself" moments in an interview. One is when the applicants might be asked to introduce themselves to the group interviewing that day and say something about themselves that might be unexpected (e.g. my twin and I have different birthdays -- we were born before and after midnight)
The other is to explain yourself to someone who did not have access to your application or who was too busy to read it. In that case, you want to give the important facts while highlighting what you'd like to be asked about. Typically, I'd like to know "where are you from (home town and university), college major, your most important research or employment or volunteer experience to date, and something unusual or fun about yourself. Finally, if you must, something about why you want to be a doctor.
We aren't supposed to ask about marital status or sexual preferences to avoid later being accused of bias in that regard but if you bring it up, it can be fair game. That said, I don't care to hear about it as I do want to tread lightly to avoid any appearance of bias.
And foreign trips, as mentioned by Goro, are not highly regarded by some adcoms.