Evolving the family tree is something nearly every Sim and their neighbor winds up doing at some point or another. On the other hand, having twins is something only a select few can achieve, as it often comes down to a roll of the dice. Though, there are ways for you to boost the odds, providing you have one or two skills, of course.
To increase your chances of having twins, you will need to invest in a massage table. The Sim giving the massage will need to be level 9 in the Wellness skill tree. Having this will open up the option to give a Fertility Massage to a receiving Sim, which, in turn, will give them a Fertility Boost.
If this doesn’t work, then you can look to purchase the Fertile Reward from the Satisfaction Rewards Store for 3,000 points. Although not a sure-fire way of conceiving twins, it will boost your odds by a significant amount.
A third and final option is to exploit the Herbalism skill in the Outdoor Retreat expansion pack. Providing your Sim is level 10 in the profession, an option to brew the Elixir of Fertility will pop up. Consuming this will increase your chances of having either twins or triplets.
For more Sims content, check out How to age up toddlers in The Sims 4 right here on Pro Game Guides.