DD set her heart on training to be an actor. Got a degree in acting (frankly, it wasn't my idea of a degree level course) never acted but worked in the media in various roles for 20 years and then, in her 40s followed up an interest in science with a few freestanding OU courses, then drifted into a OU degree in Science and engineering. She worked hard and did very well. She got snapped up by Science Reseach Centre before she had even finished her degree for her unique mix of science and media and has recently been recruited by a big technical consultancy for the same reason. They pay her a very large salary and get their money's worth and she is absolutely loving it, I have never seen her so happy and fulfilled with life.
The moral is: relax, support your children in what they want to do, unless you are very unfortunate they will muddle through and amaze you.
The other moral, is that all these recent career moves have been made in her late 40s, she is coming up for her 50th birthday, so it doesn't matter what your age. If you have the qualifications people are looking for, age doesn't come into it.