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Semi-Realistic Genetic Traits Rate

This mod significantly decreases the rate of certain genetic traits in the game to better reflect the rates of real-life genetic conditions. Most significantly, the dwarf and giant traits are now as rare as they are in real life.

Details:

Incidence rates for various genetic conditions are used. Almost all of the statistics concern the modern society, with some limiting to a certain geographical area, thus they cannot be seen as an accurate representation of medieval health. However, it is hoped that it will provide a better picture than a flat rate of 0.5% (1 in 200) applied to all traits by Paradox.

Changed traits:

Albinoism rate is decreased to 0.005% (1 in 20,000). (Marçon & Maia, 2019)
Clubfoot rate is decreased to 0.25% (1 in 400). (O’Shea & Sabatini, 2016)
Dwarfism rate is decreased to 0.01% (1 in 10,000). (Desan, 1988)
Giantism - assumed to represent acromegaly - has an incidence rate of about 0.0004% (1 in 250,000). (Colao, Ferone, Marzullo, & Lombardi, 2004, Dal, et al., 2016) However, the minimum chance that can be coded in the game is 0.001%, so that is the rate in-game.
Spindly, noted in the game files as to represent Marfan's Syndrome, has its rate decreased to 0.03% (3 in 10,000). (Judge & Dietz, 2005)
Bleeder, noted in the game files as to represent haemophilia, has its rate decreased to 0.02% (1 in 5,000). (Stonebraker, Bolton-Maggs, Soucie, Walker, & Brooker, 2010)
As the scaly trait manifests on the face, it is assumed that it does not represent ichthyosis vulgaris, which rarely affects the face. The incidence rate has been changed to the rate of moderate or severe ichthyosis, to 0.009% (9 in 100,000). (Milstone, Miller, Haberman, & Dickens, 2012)

Unchanged traits:

Wheezing is noted in the game files as to represent asthma. Its actual incidence rate is not well-known. Looking at the prevalence rate one may conclude that it is underrepresented in the game, but any adjustment is further complicated by the fact that developed countries have a far higher rate of asthma, so it is impossible to even estimate the rate in medieval societies. (Enilari & Sinha, 2019) Therefore it is left unchanged.

Hunchback is assumed to represent the Scheuermann's disease and congenital kyphosis instead of postural kyphosis, which develops naturally in old age. The incidence rate for congenital kyphosis is not well known, and the rate incidence for Scheuermann's disease is 4-8% (Tsirikos & Jain, 2011), the in-game hunchback represents the extreme end of severe Scheuermann's disease, so the 0.5% (1 in 200) rate is kept.

Lisping is underrepresented in the game, with a prevalence rate commonly thought to be 1% to 4%. (Borsel, Rentergem, & Verhaeghe, 2007) Stuttering is also underrepresented, which has a 5% incidence rate before correction. (Yairi & Ambrose, 2013) Recovery rate in medieval times is not known.

References
Borsel, J. V., Rentergem, S. V., & Verhaeghe, L. (2007). The prevalence of lisping in young adults. Journal of Communication Disorders, 40(6), 493-502. doi:10.1016/j.jcomdis.2006.12.001
Colao, A., Ferone, D., Marzullo, P., & Lombardi, G. (2004). Systemic Complications of Acromegaly: Epidemiology, Pathogenesis, and Management. Endocrine Reviews, 25(1), 102-152. doi:10.1210/er.2002-0022
Dal, J., Feldt-Rasmussen, U., Andersen, M., Kristensen, L. Ø, Laurberg, P., Pedersen, L., . . . Jørgensen, J. O. (2016). Acromegaly incidence, prevalence, complications and long-term prognosis: A nationwide cohort study. European Journal of Endocrinology, 175(3), 181-190. doi:10.1530/eje-16-0117
Dasen, V. (1988). Dwarfism in Egypt and classical antiquity: Iconography and medical history. Medical History, 32(3), 253-276. doi:10.1017/s0025727300048237
Enilari, O., & Sinha, S. (2019). The Global Impact of Asthma in Adult Populations. Annals of Global Health, 85(1). doi:10.5334/aogh.2412
Judge, D. P., & Dietz, H. C. (2005). Marfan's syndrome. The Lancet, 366(9501), 1965-1976. doi:10.1016/s0140-6736(05)67789-6
Marçon, C. R., & Maia, M. (2019). Albinism: Epidemiology, genetics, cutaneous characterization, psychosocial factors. Anais Brasileiros De Dermatologia, 94(5), 503-520. doi:10.1016/j.abd.2019.09.023
Milstone, L. M., Miller, K., Haberman, M., & Dickens, J. (2012). Incidence of Moderate to Severe Ichthyosis in the United States. Archives of Dermatology, 148(9), 1080. doi:10.1001/archdermatol.2012.1702
O’Shea, R. M., & Sabatini, C. S. (2016). What is new in idiopathic clubfoot? Current Reviews in Musculoskeletal Medicine, 9(4), 470-477. doi:10.1007/s12178-016-9375-2
Stonebraker, J. S., Bolton-Maggs, P. H., Soucie, J. M., Walker, I., & Brooker, M. (2010). A study of variations in the reported haemophilia A prevalence around the world. Haemophilia, 16(1), 20-32. doi:10.1111/j.1365-2516.2009.02127.x
Tsirikos, A. I., & Jain, A. K. (2011). Scheuermann’s kyphosis; current controversies. The Journal of Bone and Joint Surgery. British Volume, 93-B(7), 857-864. doi:10.1302/0301-620x.93b7.26129
Yairi, E., & Ambrose, N. (2013). Epidemiology of stuttering: 21st century advances. Journal of Fluency Disorders, 38(2), 66-87. doi:10.1016/j.jfludis.2012.11.002