where does half your age plus 7 come from
Age disparity in sexual relationships The "never date anyone under half your age plus seven" rule is a rule of thumb sometimes used to prejudge whether an age difference is socially acceptable.[62][63][64] Although the origin of the rule is unclear, it is sometimes considered to have French origin.[62]
Middle age According to the Oxford English Dictionary middle age is between 45 and 65:[2] "The period between early adulthood and old age, usually considered as the years from about 45 to 65." The US Census lists the category middle age from 45 to 65. Merriam-Webster list middle age from 45 to 64,[3] while prominent psychologist Erik Erikson saw it starting a little earlier and defines middle adulthood as between 40 and 65. The Collins English Dictionary, list it between the ages of 40 and 60.[4] and the Diagnostic and Statistical Manual of Mental Disorders - the standard diagnostic manual of the American Psychiatric Association - used to define middle age as 40 to 60, but as of DSM-IV (1994) revised the definition upwards to 45 to 65.