Rent plus childcare is simply too much for many in Marin. According to data compiled by the First 5 Marin Children and Families Commission, a family of four with an infant and a preschooler needs an annual income of $102,223 to afford the basics of family life. Nearly 35 percent of such families in Marin—there are around 10,000—do not meet that standard. The commission, which guides the county Board of Supervisors on the investment of…