Since being gay is a choice this will be an impossible test to develop. Though prochoice liberals will deny this.
Check it out:

A medical test being developed by Kuwait will be used to ‘detect’ homosexuals and prevent them from entering the country – or any of the Gulf Cooperation Countries (GCC), according to a Kuwaiti government official.

GCC member countries – Bahrain, Kuwait, Qatar, Oman, Saudi Arabia and the United Arab Emirates – already deem homosexual acts unlawful.

This controversial stance is being toughened, according to Yousouf Mindkar, the director of public health at the Kuwaiti health ministry.

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