I hadn't remembered that shortly before the planned wedding to Jason, Elizabeth was looking in the family bible and it listed the family members and their birthdates - Roger - September 14, 1925, Elizabeth - February 28, 1917, and Carolyn - July 16, 1946. We often speculate about Carolyn's and Vicki's ages. In the flashback conversation between Elizabeth and Paul, Carolyn is mentioned as being 2, and Elizabeth was "confined" to Collinwood for 18 years = 20, which 1946 to 1966 would be. So, they were consistent that time!
What surprised me was that Roger, 8+ years younger than his sister is listed first and she's underneath!!