Tex. Ins. Code § 544.155

Notwithstanding any other provision of this subchapter, a health benefit plan issuer or life insurer may underwrite a risk on the basis of an individual's physical or mental condition regardless of the underlying cause of the condition or on the basis of any underwriting criteria not prohibited by this code or another insurance law of this state or a rule adopted under this code or another insurance law of this state if the issuer or insurer consistently applies the criteria and does not merely use the criteria as a pretext to evade the application of Section 544.153.