Appendix: Scenarios

After each scenario (below) were the question “What are the chances that [name of child] will have sickle cell disease?” and the response scale from “No chance” to “Every chance.”

Main design

1-Mr. De Souza is not a carrier of the gene of sickle cell disease. Mrs. De Souza is not a carrier either. They just had a son: Gérard.

2-Mr. Tossou is a carrier of the gene of sickle cell disease. Mrs. Tossou is not a carrier of the gene. They just had a son: Léopold.

3-Mr. Agbohassickle cell disease. He suffers from it in his daily life. Mrs. Agbois not a carrier of the gene. They just had a son: Matthias.

4-Mr. Tchibozo is not a carrier of the gene of sickle cell disease. Mrs. Tchibozo is herself a carrier of the gene. They just had a son: Yvon.

5-Mr. Tchané is a carrier of the gene of sickle cell disease. Mrs. Tchané is also a carrier of the gene. They just had a son: Raïmi.

6-Mr. Do Regohassickle cell disease. He suffers from it in his daily life.Mrs. Do Rego is simply a carrier of the gene. They just had a son: Adédjouma.

7-Mr. Dadjo is not a carrier of the gene of sickle cell disease. But Mrs. Dadjohas sickle cell disease. She suffers from it in her daily life. They just had a son: Gildas.

8-Mr. Gbètoho is a carrier of the gene of sickle cell disease. But Mrs. Gbètoho has sickle cell disease. She suffers from it in her daily life. Theyjust had a son: Auriol.

9-Mr. Kolawoléhassickle cell disease. He suffers from it in his daily life. Mrs. Kolawolé also suffers from thisdisease. They just had a son: Antoine.

10-Mr. Gbaguidi is not a carrier of the gene of sickle cell disease. Mrs. Gbaguidi is not a carrier either. They just had a daughter: Isabelle.

11-Mr. Dagba is a carrier of the gene of sickle cell disease. Mrs. Dagba is not a carrier of the gene. They just had a daughter: Christiane.

12-Mr. Mama has sickle cell disease. He suffers from it in his daily life. Mrs. Mama is not a carrier of the gene. They just had a daughter: Silifatou.

13-Mr. Sossou is not a carrier of the gene of sickle cell disease. Mrs. Sossou is a carrier of the gene. They just had a daughter: Solange.

14-Mr. Guinnou is a carrier of the gene of sickle cell disease. Mrs. Guinnou is also a carrier of the gene. They just had a daughter: Suzy.

15-Mr. Nahum hassickle cell disease. He suffers from it in his daily life. Mrs. Nahum is simply a carrier of the gene. They just had a daughter: Karamatou.

16-Mr. Eyebiyi is not a carrier of the gene of sickle cell disease. But Mrs. Eyebiyi has sickle cell disease. She suffers from it in her daily life.They just had a daughter: Carmen.

17-Mr. Tognisso is a carrier of the gene of sickle cell disease. But Mrs. Tognisso has sickle cell disease. She suffers from it in her daily life. They just had a daughter: Colombe.

18-Mr. Akéhas sickle cell disease. He suffers from it in his daily life. Mr. Aké also suffers from sickle cell disease. They just had a daughter: Antoinette.

Six additional scenarios to test the absence of information

19- Mrs. Vignigbé is not a carrier of the gene of sickle cell disease. She just had a son: Alexandre. His father was killed during an accident. He never had genetic testing.

20-Mrs. Fadiga is a carrier of the gene of sickle cell disease. She just had a son: Alain. His father was killed during an accident. He never had genetic testing.

21-Mrs. Alia has sickle cell disease. She suffers from it in her daily life. She just had a son: Cocou. His father was killed during an accident. He never had genetic testing.

22-Mrs. Kouadio is not a carrier of the gene of sickle cell disease. She just had a daughter: Amanda. Amanda’sfather was killed during an accident. He never had genetic testing.

23-Mrs. Bola is a carrier of the gene of sickle cell disease. She just had a daughter: Minoushka. Minoushka’s father was killed during an accident. He never had genetic testing.

24-Mrs. Sagbohassickle cell disease. She suffers from it inher daily life.She just had a daughter: Bitia. Brita’s father was killed during an accident. He never had genetic testing.

Twoadditionalscenariosto test contagion

25-Mr. Jouable is not a carrier of the gene of sickle cell disease. Mrs. Jouable is not a carrier either. They have a son: Didier. Didier has been raised by a nanny who has sickle cell disease and who suffers from it in her daily life.

26-Mr. Akadiri is not a carrier of the gene of sickle cell disease. Mrs. Akadiri is not a carrier either. They have a daughter: Razmir. Razmir has been raised by a nanny who has sickle cell disease and who suffers from it in her daily life.