We don't recall exact details of this, but it seems like the info posted in the Genforum was wrong, just by inspection. As we noted the California researcher seemed convinced that G P Peck's mother was Irish, and not from Missouri. We believe that she went back to Ireland for a short while, then came back to the states with young GP Peck, eventually moving to California. The father of GP Peck, is alleged to have drowned in the Erie Canal shortly after the birth of his son, about 1886.
Hopefully another person can straighten this thing out. If that California researcher had published and documented his work, it would be more accessible. Relying upon 10 or 15 year old memories is a notoriously inaccurate method.