Mrs. McCain's uncertainty about the precise tally of her siblings, coming on the heels of her husband's confusion about the number of the couples' homes, might not be as big a problem for the McCain campaign as some might expect, says Davis Logsdon, professor of economics at the University of Minnesota. "As long as the couple has more homes than half-sisters, they could easily house one of the half-sisters in each of the residences and keep them happy," Dr. Logsdon says. "However, if the number of half-sisters grows faster than the number of homes, that could potentially lead to crowding."