中間性的原因- 激素因素

先天性腎上腺增生性肥大患兒從其父母遺傳有兩個異常的基因，也就是說，從父母各遺傳一個異常基因。就像在大多數病例那樣，當父母的一方只有一個這樣的異常基因時，父母雙方本身可能沒有臨床症狀。所以，父母只是“先天性腎上腺增生性肥大顯性基因攜帶者”。不過，甚至於如此也並不必定意味著他們會將異常基因遺傳給子女。事實上，不會遺傳上這個基因的幾率是1/4，也就是說，如果他們有４個孩子，只有一個會患上先天性腎上腺增生性肥大(即只有一個孩子會顯現出臨床症狀，但是另有兩個孩子會是這個異常基因的攜帶者。——譯者注)。儘管總人口中異常基因攜帶者約占２％，這就解釋了為什麼先天性腎上腺增生性肥大在臨床上非常罕見的原因。

母親／Mother     父親／Father   無病症／no symptoms 非異常基因攜帶者 ／not a carrier 有症狀異常基因攜帶者 symptomatic carrier   無症狀異常基因攜帶者 asymptomatic carriers

Causes of Intersexuality - Hormones

Children with CAH have two abnormal genes inherited from their parents, i.e. one from each parent. The parents themselves may not have the condition when, as in most cases, each of them has only one of these genes. Thus, they are only “carriers of the CAH trait”. However, even this does not necessarily mean that they will pass it on to all of their children. In fact, the odds are one in four, i.e. if they have four children, only one will have CAH. This explains why CAH is quite rare, although ca. 2% of the general population are carriers.