Therefore, we suggest that the variability in serotonin may not be best understood as a marker for religiousness, per se, but as a marker for a more general character trait found in both religious and nonreligious people. It would be interesting to repeat a similar study within two populations of religious and secular subjects. We suspect that within both populations, a subset might have lower binding potentials that would correlate not only with "spiritual acceptance" but also with the metrics of mystical experience and perhaps recreational drug use. Finally, given the hypothesis that self-transcendence is environmentally influenced by the differences between Swedish and American cultures, it would be interesting to further test this hypothesis by comparing the results in Sweden and the United States with a population drawn more from the openly mystical contexts found in some African or aboriginal cultures.