Short answer:
No. There is no evidence, and naturally no concrete evidence at all.
Long answer:
Because of the Fukuda diagnostic criteria, (self reported fatigue and 4 or more non proven symptoms) CFS can never exist as transmittable disease or genetic disorder.
CFS is a clinical diagnosis, like a headache or pain. These may or may or not exist, it's what the person reports. A doctor cannot 'test' for these, because CFS 'tests' are exclusionary not based on inclusion.
But...people with vary reasons for ill health diagnosed with CFS exists. People's suffering is real, so they are sick and need researching biomedically.
But then we come back to square one. The people who need researching, no one can ever tell who 'they' are, as no one needs to demonstrate illness at time of diagnosis. Due to this people will present with many reasons for being sick. These range from active infections, autoimmunity, neurological, allergic to cardiac to hormonal, to circulatory to psychosomatic.
Thus it's impossible to answer the question if 'CFS' is transmittable.
You can however notice than may infections are passed on, and thus if the male is impregnating the female, then it's not impossible the female is then infected and her baby becomes so too. On that basis, if you can prove the same strain of infection (e.g. Lyme) or a man with CFS who then gives it to his sexual partner, and she wasn't sick before and/or their baby wasn't sick before, the on this hypothetical basis, a person's 'CFS' (that is then a misdiagnosis because of the diagnostic criteria!) is hereditary.
An infection, be it bacterial, viral or retroviral can be passed on by either sex.
If this comes to light in 'CFS' at a rate of 0.1% or 10% or 25% we shall have to wait and see just how widespread non tick based Lyme actually is (the majority of chronic lyme patients have their diagnosis denied and their official diagnosis was, or is CFS).
Read this for ideas:
https://www.lymedisease.org/lyme-sexual-transmission-2/
In the study, researchers tested semen samples and vaginal secretions from three groups of patients: control subjects without evidence of Lyme disease, random subjects who tested positive for Lyme disease, and married heterosexual couples engaging in unprotected sex who tested positive for the disease.
As expected, all of the control subjects tested negative for Borrelia burgdorferi in semen samples or vaginal secretions. In contrast, all women with Lyme disease tested positive for Borrelia burgdorferiin vaginal secretions, while about half of the men with Lyme disease tested positive for the Lyme spirochete in semen samples. Furthermore, one of the heterosexual couples with Lyme disease showed identical strains of the Lyme spirochete in their genital secretions.
“The presence of the Lyme spirochete in genital secretions and identical strains in married couples strongly suggests that sexual transmission of the disease occurs,” said Dr. Mayne.
“We don’t yet understand why women with Lyme disease have consistently positive vaginal secretions, whilst semen samples are more variable. Obviously there is more work to be done here.”
Dr. Stricker pointed to the unknown risks of contracting Lyme disease raised by the study. “There is always some risk of getting Lyme disease from a tickbite in the woods,” he said. “But there may be a bigger risk of getting Lyme disease in the bedroom.”
Reference: The Journal of Investigative Medicine 2014;62:280-281.
