The age difference between the spouses in marriages used to be at least 8 to 11 years. According to Jathakam, there should be a significant age difference between the spouses in order to prevent the influence of one partner's rashi and nakshatra on the other. Couples today tend to be only 1-2 years apart in age, which means that whatever one partner does will effect and resemble what the other does.
Online Jathakam