Realistic Lifespans  

Description
The lifespans in The Sims 4 are not realistically balanced. Your Sims do not have enough time to go to university, enjoy young adulthood, date, get married, raise a family, and finally become an empty nester and enjoy their retirement.
 
In the game, the toddler and child ages added together take the same amount of time as the adult age. In real life, the toddler and child ages take 12 years. If we consider adulthood to be ages 30-65, that’s 35 years! More than double what being a toddler and child should be.
 
I have created this mod to rebalance the life stages to be more realistic. I have based the ages around the metric that 2 Sim days is equivalent to one real-world year. This keeps the younger ages about the same length, while extending the older stages.
 
Adjusted Ages:
Baby 2 days --> 0 to 1 year old
Toddler 8 days --> 1 to 5 years old
Child 14 days --> 5 to 13 years old
Teen 10 days --> 13 to 18 years old
Young Adult 20-28 days -> 18 to [28 or 32] years old
Adult 68 to 72 days --> [28-32] to [62-68] years old
Elder 16 to 24 days --> [62-68] to [70 to 80] years old

The active trait will increase your lifespan by 10% bringing you up to a maximum of 88 years.
The long-lived aspiration reward trait will increase your lifespan by 25% bringing you up to a maximum of 100 years.
The active and longevity trait combined will increase your lifespan by 35% bringing your maximum lifespan to 108 years old.

Short and Long Lifespans:
Adding this to your mods file will override your short, normal, and long lifespans. The short lifespan will be half the length as what is described above. The normal lifespan will be exactly what is described above, and the long lifespan will be four times the length as what is described above. 

Pets
This mod does not affect pets. But I would still recommend this mod if you play with pets. Pets' lifespans are already balanced around the idea that 2 in-game days is worth a year of aging. Here is the breakdown of pets' lifespans (written in duration of the lifespan as opposed to total age):

Cat:
Kitten: 3 days --> 1.5 years
Adult: 21-24 years --> 10.5-12 years
Elder: 6-8 days --> 3-4 years
Bringing the lifespan of a cat to 15-17.5 years

Dog:
Puppy: 3 days --> 1.5 years
Adult: 17-20 --> 8.5-10 years
Elder: 5-7 years --> 2.5-3.5 years
Bringing the lifespan of a dog to 12.5-15 years

Versions
nifflr_realistic-lifespan.rar is the original version of the mod. If you want the mod as described above, only download this file.

You can now download a x2 version. This version has lifespans that are exactly twice as long as in the original mod. 4 sim days now represents one real-world year of aging at the normal speed. If you are using this mod and have Cats & Dogs installed, you should also download the Pets x2 file so that pets will age twice as slowly as well.

Do not use the x2 file and the original file at the same time. Only use pets-lifespan-x2 if you are using the realistic-lifespan-x2 AND have Cats & Dogs installed. You do not need to modify the pets lifespan if you are using the original mod.