My first family got a set of twin girls after their first child. The the second gen, same family, got back to back twins (boys and girls) first and second try. Did not buy baby boost for either set. Did buy BB twice in one other family because I kept trying and took six years for their first. Finally gave the boost to the husband and wife (same time) no luck and took twelve years for second child, I no longer buy BB. No twins in the third gen of my first family, but then I have not received a set in any family after upgrading to 100.05.
LauraLee