If God does not make mistakes, then how do you explain people that are intersex? I'm not saying God makes mistakes, but I can see how easily someone could argue that since people that are intersex exist, then the gender they were born could easily be a mistake.
When a child forms in the womb, it has two reproductive organs. In normal development a set of XY chromosomes causes androgens to be present in the child's bloodstream. The reproductive organs respond to the hormones to form testicles that move down and eventually out into the scrotum which was shaped in response to the hormones. A set of XX chromosomes causes estrogens to be present. The reproductive organs respond to form ovaries which remain in the internal cavity of the abdomen and the vulva and vagina externally.
Intersex, which used to be called hermaphroditism, is when a birth defect occurs. Intersex technically is when the external genitals don't match the reproductive organs. For example, a girl could have all or part of the external equipment of a boy but has ovaries internally. A boy could have the external equipment of a girl but have testicles internally.
There are several subclasses of intersex.
- A girl could have XX chromosomes, but her external genitals take on the appearance of a male, in whole or more often in part. A mother having exposure to testosterone during a critical phase of development is one known cause of this condition. The most common cause is a defect in the adrenal gland that keeps estrogen from being manufactured and thus androgens end up dominating.
- A boy could have XY chromosomes, but his external genitals don't form properly giving him the appearance of a girl. The most common cause of this is when the testes don't form properly and therefore aren't able to produce the required androgens. Since the formation of the sex hormones is a multi-step process, any failure in the steps can cause a problem, including failure in the adrenal gland.
- There are cases when a child ends up with one teste and one ovary despite having the proper XX or XY chromosomes. This is usually traced back to a genetic defect. There are a few individuals who somehow end up with a mix of XX and XY chromosomes in their cells. The cause is unknown, but studies of animals with these symptoms have been linked to exposure to certain pesticides.
- Finally, there are some who end up with an extra chromosome and thus have XXY or XXX. Usually, these don't produce a discrepancy between the internal and external reproductive organs, but they do end up with the wrong level of male or female hormones in their bloodstream which causes problems.
Just because a birth defect has taken place, it does not justify people choosing to be a different sex than what they were born. It is no different than other problems, such as missing limbs or extra fingers or toes.
Transgender is when a person who has normal chromosomes and normal hormones argue that he should be of the other sex because of how he feels. This is a choice, not a birth defect. The existence of intersex birth defects does not justify transgender choices. Transgender is a dissatisfaction with how God made him.