Another "alternative lifestyle" of today that breaks a previous social norm is non-traditional families. Once, the "nuclear family" was considered normal: a working father, stay-at-home mother and two kids.
Consider the television progression. Are you young enough to remember The Dick Van Dyke Show or Leave it to Beaver? Even The Simpsons and Family Guy portray this traditional family (although Family Guy adds a talking dog and grown up baby, so that might be a bad example).
Now families come in sorts of socially acceptable varieties. Two moms, two dads, unmarried men and women living together, mixed races, adopted children. Shows like Brothers and Sisters, Two and a Half Men, or Will and Grace portray non-traditional structures of what could be argued as more than just roommates, but families.