Loom

According to one view of Gallifreyan history, Looms were used by Time Lords to perpetuate their race in the wake of Pythia's Curse. Unable to procreate sexually, the Time Lords had to rely on the Rassilon-invented devices to "weave" new life from genetic material. (NA: Cat's Cradle: Time's Crucible, Lungbarrow)

According to Leela, each Family on Gallifrey had their own "Family Loom" which they used to create new members of their Family. She felt pity for Gallifreyans, because the Looms prevented "true children" from existing on their planet. Gallifreyans were born as "full-grown adults", although they were child-like at the time of their birth, and had to mature mentally like any young life-form. The genetic relationship between people originating from each Family Loom was lateral rather than direct, meaning that people from the same Loom were "cousins" of each other. (NA: Lungbarrow)

Looms also kept a tally of all the people they birthed, and could normally indicate how old each of its "offspring" was and how many regenerations each had gone though. Data from all the Family Looms on Gallifrey was sent to the Bureau of Loomographic Records, which served as a central repository of genetic information.

A Loom was given to each of the Houses of Gallifrey, and each House had a specified number of cousins which could exist in the Family at any given time. The House of Lungbarrow, for example was allotted 45 cousins. When a member of a Family died for the final time, the Loom would weave a new cousin into the Family. Cases did exist when an additional cousin was woven (such as the Doctor's cousin Owis) but were extremely rare, as such a thing was illegal. When he was only five years old, the Doctor boasted that he could remember existing in the Loom before he was actually born:

"I can remember waiting to be born...It was like being all strung out. All unravelled inside the Loom. I was spread really thin…I couldn’t think. Not put thoughts together. … But I knew where I was and what was happening. I couldn't wait to get out. And then I was born. My lungs nearly burst. The first rush of air was so cold...."''"

- The Doctor

The Eighth Doctor once said that he was loomed, yet remembered having parents and a childhood. He knew that one of these was a dream, but could not recall which. (EDA: The Shadows of Avalon)

Behind the scenes
Like many ideas and concepts introduced within non-television based media, this has not been referenced on-screen, and like many ideas and concepts, can be seen to contradict sources within the series itself. (This is an almost regular occurrence within Doctor Who of almost every era.)

There have been many statements by the Doctor in televised and non-television based media referring to him being a "boy" or showing other Time Lords as children, in DW: The Time Monster the Doctor tells Jo a story referring to when he was a "little boy", whilst in DW: A Good Man Goes to War the Doctor reveals a cot that was his. In DW: The Sound of Drums the Master is shown in a flashback-like sequence as a child.