Why did many women in virginia not start a family until their mid-twenties?

The main reason is Immigration of women promoted by colony which includes Tobacco brides for arranged mairrages. Men in Virginia outnumbered women due to the demand for male servants to work in the tobacco fields so they usually had to complete their terms of service before marrying, they did not begin to form families until their mid-twenties. This lead to the lack of essential element of English society.