The family's Catholicism was practiced behind closed doors. His three older brothers followed in the Catholic tradition. The eldest was the Royalist soldier Colonel Sir Henry Gage (1597–1645), who fought on the Continent for Catholic Spain and eventually in England for Charles I. According to J. Eric S. Thompson, Henry Gage "strove entirely to eradicate all remembrance of Thomas and his misdeeds from his mind." George was a diplomat and priest, who also disavowed "my graceless brother"; and William was a Jesuit.