After the death of Sage parasurama 's mother . Parasurama vowed to annihilate the kshatriya race . (imagine a brahmin undertakes a terminator job which is quite outlandish by today's standard). In order to safeguard their children, kshatriya sent their sons and daughters to the brahmin households. At their homes, kshatriya children would look alike of brahmin children.But, the shrewd parasurama knew the knack of separating kshatriya's children. He would ask the brahmin lady to arrange for a meal and ask all children to have meals on a single platter.
Under any circumstances, brahmin would never share meal with anyone as it would pollute him/her. Through this trick sage Parasurama would continue with his "project".
If you analyse why they don't share meals with other is because it is considered as an unhygienic practice and that human saliva carries various bacteria and viruses. Remember, we live in the days of H1N1 virus . Every doctor stresses on personal hygiene .
When you compare today's Brahmin with the brahmins of that era . I'm sorry today's brahmins are brahmins for namesake. They could stoop to any level to achieve their "goals" in their life.
In today's world, majority brahmins have relinquished their rituals as they mix freely with outer world. The members from other community view the minority portion of the brahmin community (who try to ape their forefathers but not following exactly)with a ridicule . When others have changed why you with an outdated ideology?