|Gwen and Olivia Lynch|
| No image available|
|Portrayed by||Tonya Glanz|
|First seen||The Leviathan|
|Residence||New York City, New York, U.S.|
Gwen and Olivia Lynch are identical twin sisters living in New York City.
They have a semi-frequent sexual relationship with Sherlock Holmes, who describes their interaction as "mutually beneficial": their contact allows him to study the differences between two people who are otherwise genetically identical (according to him, there are seven major differences between the Lynch Sisters). As to what they get in return, Joan Watson cut him off before he could explain, but both sisters bid a fond farewell to Sherlock when they departed The Brownstone after their last rendezvous.
|Season one appearances|
|Pilot||While You Were Sleeping||Child Predator||Rat Race|
|Lesser Evils||Flight Risk||One Way to Get Off||The Long Fuse|
|You Do It to Yourself||The Leviathan||Dirty Laundry||M.|
|The Red Team||The Deductionist||A Giant Gun, Filled with Drugs||Details|
|Possibility Two||Déjà Vu All Over Again||Snow Angels||Dead Man's Switch|
|A Landmark Story||Risk Management||The Woman||Heroine|
- Gwen and Olivia are actually played by a single actress, Tonya Glanz.
- According to Sherlock Holmes, there are seven major physiological differences between the Lynch sisters, despite their being genetically identical. One noticeable difference is that Gwen wears glasses.