No, I don't think that's the case. I mean, depression is very situational, but the clinical form also has many genetic factors.
My mom had me after the age of 35 (she was 37 when she had me) and I do indeed suffer from clinical depression-however, I'm pretty sure it's largely a genetic component there as she has it herself. On top of that, her father suffered from it as well, as did his mother. Both of my mom's older siblings (she's the youngest of three children) have it as well. With all of these generations having it, I'm pretty sure there's some genes there being passed down.