Robert de Vere, 3rd Earl of Oxford, Surety of the Magna Carta - Date Conundrum

After seeing Alice's birth year and this birth year related to the mother's birth year, the mother's birth year is neither realistic nore valid.
With Alice, her profile shows her as being born well before her mother.r
With this profile, Agnes appears to have conceived Robert when she was about age 11 and gave Birth at age 12.