After examination of the data, which revealed a pattern of decrease followed by increase in some sequences of correlations, an additional statistical calculation was carried out for each sequence of correlations: using a randomization test, test whether the difference between the minimum value, taken over the entire age range, and the value at age 25 in the observed sequence of values could be the result of random fluctuations around the trend from age 12 to age 25. For testing whether the increase in correlation from the minimum value to that at age 25 was the result of random fluctuations around the trend, the null hypothesis was that the sequence of correlation values was like a random walk, with the sequence of increments (differences between successive values) between successive correlation estimates randomly drawn from the realized increments, with the resulting difference between the minimum value, taken over the entire age range, and the value at age 25. The statistical characteristics of the null hypothesis were determined by cumulative summation of each of 1000 permutations of the realized increments to provide 1000
