Taylor Swift's hot younger brother, Austin Swift, rang in his 24th birthday on Friday, and Taylor marked the special occasion with the ultimate throwback photo. The singer, who recently celebrated her one-year anniversary with boyfriend Calvin Harris, shared an adorable childhood snap of herself and Austin cracking up, writing, "HAPPY BIRTHDAY AUSTIN!!!!! Thanks for 24 years of LOLs. @austinkingsleyswift." Of course, this isn't the first time Taylor's taken a trip down memory lane. Back in September, she melted hearts everywhere when she posted a flashback shot of herself and her brother on a tractor. See the precious snap above now, and then check out what Austin recently said about Taylor's feud with Kanye West.