Doc, take an awl or Phillips screwdriver and try to poke into beams, especially around edges/ends. If it easily penetrates you've got rotted or infested wood. Tel-tale hint of termites are sand-like tunnels, usually around outside edge of foundation and/or along masonry (basement/crawl space) floor and walls. If you see any evidence, don't fool around, get a certified pest control outfit to inspect. If they find infestation have the whole house treated = don't just treat the area(s) identified = you'll just be chasing them around. I'm not an expert by any means but have had termites in a previous home and at two places of prior employment. Good luck with your family's new home.