Daughter of decedent failed to carry her burden of proof under Prob. Code 21622 that the sole reason she was omitted from the decedent’s trust was because the decedent was unaware of her birth. The trust also omitted four other children that the decedent had had out of wedlock, naming only the two children he had with his wife. That demonstrated a plan of distribution excluding illegitimate children, of which the petitioning daughter was one.