Questionnaires will be completed by each member of the twin set. A board-certified dermatologist will examine each member to categorize the type and severity of their rosacea. The facial and gut microbiome will be sampled and sent for microbial analysis.

1. Twin set subjects will be administered a questionnaire regarding demographics (age, gender, state of residence, time lived together, birth order), rosacea duration, prior rosacea treatment, diet (and similarity of diet to twin), co-morbidities, signs and symptoms suggestive of cardiovascular or gastrointestinal disease/disorder.
2. Subjects will be examined by a board-certified dermatologist and global assessment, inflammatory counts and clinician's erythema score will be performed. Eyes will be examined for signs of ocular rosacea.
3. Facial microbiome sampling will be performed on-site utilizing a kit manufactured by UBiome. The skin with active rosacea will be swabbed and the swab immediately placed in sample medium. The tube is then shipped to the manufacturer for 16s rRNA shotgun metagenomics to identify resident bacterial genera and species. (16) This can be compared to their extensive library of normal controls, to the other member of the twin set and to acne subjects.
4. Subjects will be given a fecal microbiome kit for home sampling. Feces obtained from toilet paper is collected and placed in the sample medium. Subjects can either ship directly or return to the study site for shipping.

Inclusion Criteria:

1. Presenting with monozygotic or dizygotic twin
2. One or both twins with facial rosacea
3. Willingness to allow facial and fecal samples to be analyzed -

Exclusion Criteria:

1. Non-twin siblings
2. Absence of facial rosacea in both twins -

Attendees at the Twins Days Festival Monozygotic or dizygotic twin sets Facial Rosacea

There is no plan to share any IPD with other researchers