I have seen that the ratio of Tamil Brahmana (Iyer+Iyengar) men to women is typically 2.5:1 in the following websites:
brahminsmatrimony.com
tamilmatrimony.com
shaadi.com
jeevansaathi.com
And a couple of other websites. It may indicate that either more men, or their parents, post their profiles compared to women, or there is a genuinely skewed ratio of unmarried Tamil Brahmana men/women. Given that one needs to become a member of the above websites in order to contact someone else, it is highly unlikely that women or their parents are not choosing to register at these sites. Also, as far as I am aware, very few Brahmanas practice female foeticide unlike some other communities, so the actual ratio of Brahmana women to men in the population should be relatively equal.
It may be that relatively few Brahmanas are using the internet for matrimonial searches, mostly relying on newspaper and magazine classifieds, where the ratios may not be so skewed. A grimmer explanation may be that many Brahmana women, particularly good looking ones, are getting taken out of the marriage pool in college or at the workplace. Until a few decades ago, Brahamana men and women were almost guaranteed to marry into a Brahmana household because of conservative attitudes and family pressures, preserving Brahmana culture for thousands of years. However, all that has now changed.
If the above skewed ratios on the internet are reflective of those in the general population, it is quite possible that nearly 2/3rds of unmarried Brahmana men are going to face problems in marrying into a Brahmana household. In another 2 generations, Tamil Brahmanas may end up like the Parsis of India, a tiny and irrelevant community looked upon with curiosity. For those of us who have been lucky enough to be able to find a Brahmana spouse, I feel it is incumbent upon us to at least try and preserve our culture for all communities in the future, since there is a very real possibility that our community may be extinct genetically in the near future.
Sociologists proclaim that it is the women of a community who are to a large extent responsible for preserving the culture. Some of the good values and principles of Brahmana culture, like non-violence, intellectualism, vegetarianism, spirituality etc, may then find its way into general Tamil society through the outmarriages.