The largest was I'm afraid, negative.
Dad was a Chartered Electrical Engineer, a scientist in a Government department. His establishment was closed wholesale and a huge number of employees and their families moved to a new, custom-built site about 100 miles away.
I was only seven, in my last Year at Infants' School.
By a stroke of total lack of communication between Departments, it was right in the middle of the schools' Summer Term. I can't think of any other explanation as the country's education system was, rightly, also State-run with similar, largely-coherent term times and curriculae nation-wide. So it only needed one lot to talk to another lot to agree when best to move our lot.
'Best' would have been a couple of months later, in the long Summer Holiday (six weeks) so far less disruptive to so many people.
Many fellow-pupils took it in their stride and indeed some excelled irrespectively of it; but the change was too great for me, especially in Arithmetic for some reason. So I was never much good at anything numerical since; although I did catch up a bit in later life.
So that scuppered my chances of following my dream of science or engineering career, although of what sort i was never certain, since both disciplines are highly mathematical.
(Engineering can be defined as applying scientific knowledge to practical ends; and some areas require very advanced mathematics indeed.)
.....
Still, with a technical streak within my family I did develop and still follow a broad interest and largely-lay knowledge in science and engineering, and did work at "shop-floor" level in various ways in those fields.