The phrase "are said to develop" is correct and usable in written English.
It can be used when discussing beliefs, claims, or observations about a process or phenomenon that is thought to occur.
Example: "These skills are said to develop over time with consistent practice and dedication."
Alternatives: "are believed to develop" or "are thought to develop".
Norms contribute to the functioning of the social system and are said to develop to meet certain assumed "needs" of the system.
People are said to develop attention deficit hyperactivity disorder (ADHD), due to the information and interaction overload.
In popular understanding blind people are said to develop more acute senses in other areas, but recent research indicates that the brain may actually be able to substitute one sense for another.
In technical terms, a thunderstorm is said to develop when the atmosphere becomes "unstable to vertical motion".
The basic concept for Hull was "habit strength," which was said to develop as a function of practice.
During the 10-minute segment, the gray model is said to overheat and the silver Roadster is said to develop "broken" brakes.
That high-performance version is said to develop more than 550 horsepower — up from 500 of the current V-10 model — with a twin-turbo V-8.
In clinical literature, codependency is said to develop from a person's childhood attempts to adapt to dysfunctional family life e.g., life in which parenting is abusive, neglectful, inconsistent, or otherwise seriously ineffective.
An early literary essay, for instance, was her revelatory article The Wearing Out of Genre Materials (1971) – ideas and tropes in genre fiction were said to develop through three distinct phases: innocence, plausibility and ultimately decadence.
Note that if evolutionary change truly were progressive, life could be said to develop instead of evolving (Werth 2005; Chorost 2012).
The stimulation of the brain through "appropriate" care giving, (that is by the carer talking, singing and reading to very young children), is said to develop neural networks and promote brain growth.
