Being born in Moola nakshatra is not a sin nor anything bad is going to happen to you. One out of every 27 people are born in Moola star. And within that one out of four are born in the first pada. Do you mean to say that one out of 108 people have something to worry on account of this. These are all superstitions prevailing and Astrology never considers them as taboos. These sort of rumours are spread by illiterate astrologers.
What really matters is only the placement of planets in your chart at the time of your birth and this can be give you some insight into your life based on well illustrated calculations provided in Astrology.