It's long been established that astrology is a bunch of bunk, but it's also a well-known fact that other outside forces during pregnancy and birth do have effects on babies. Recent studies suggests that birth month can affect your baby's personality, according to TIME. That doesn't mean that all Cancers are really overly sensitive crabs, but the season a baby is born could contribute to an increase in the likelihood of certain traits. A word of caution: nothing conclusive has been hammered out just yet, so don't base your family planning on the findings. But if you're inclined to worry and you just conceived in the last month or so, you might want to stop reading.
The studies found that babies born in the Spring tend to be more optimistic, but they also face the greatest risk of clinical depression. Some Summer babies are similarly optimistic, while others lean towards cyclothymia, or the rapid cycling between high and low moods. Cyclothymia shouldn't be confused with bipolar disorder, though; August babies actually have the lowest incidence of bipolar disorder diagnoses. Fall babies are the most even-tempered of all, experiencing lower levels of both depression and bipolar disorder, but they do tend to be more irritable. Nothing too bad so far, right?
All those lows have to be offset with highs somewhere else, so perhaps you can see where this is going: Winter babies bear the brunt of all the unfavorable characteristics, experiencing higher levels of schizophrenia, bipolar disorder, seasonal affective disorder, and depression. On the plus side, they're more creative and imaginative, and more likely to become famous, so if you've always wanted to raise a tortured artist, now's the perfect time to get pregnant.
Again, these are just general trends, and there are an infinite number of factors that go into determining who a person becomes. Some studies imply that birth order might play a role in personality and intelligence, or even sexual orientation. Population stress, like natural disasters, recessions, and war, can even have a hand in determining the baby's sex at birth. But the biggest determining factor in a baby's personality is probably still the way that they're raised, so while parents don't have to worry about conceiving in the wrong month, they'll still be able to second-guess their education choices, discipline style, and permissiveness with screen time for the rest of their lives, and rest comfortably with the knowledge that their kids will surely find any number of ways to blame them for everything.