The policy of the show is to have Tabatha "grow" a bit faster than a baby would in real life. Hence the necessity of hiring slightly older baabies every few months. As a result, the stint of the Gentry twins was also over in a fairly short time. Their places were taken by the twin daughters of Mrs. Stephen Young, who were born on June 24, 1965. The Young girls are called Julie and Tamar, and you can see pictures of them on pages 36 and 37 of this issue (top of page, second row, left --ED). They have a sister named Zoe Young. 

June 24th, 1965 in Los Angeles (Age 59)