The Tories remain "under-represented" in the Lords, ministers have said, in response to anger over the ennoblement of nine mainly ex-ministers on Friday.
Raising the issue, Labour's Lord Adonis said the Conservatives now had 63 more peers than Labour, despite having no parliamentary majority in the Commons.
This was a "clear and fragrant breach of the constitution", he claimed.
But Lord Young said there was no requirement for any parity and Theresa May had shown "commendable restraint".
Even with the new appointments, the former transport secretary and Conservative chief whip said that his party had fewer than a third of the peers in the largely unelected upper chamber.
The government, which does not have a majority in the Lords, has been regularly defeated in the house since Theresa May became PM, including 15 defeats alone on the flagship EU Withdrawal Bill.
On Friday, the PM announced peerages for six former MPs, including Sir Eric Pickles, Peter Lilley and Edward Garnier, and three others as part of a belated dissolution honours list after last year's election.
Lord Adonis questioned how Mrs May, despite leading a minority government, was justified in announcing a list with three times as many Conservative names on it as Labour ones.
The last Labour government, he said, left office with just 26 more peers than the Tories despite having a Commons majority that was huge by contemporary standards.
Lord Adonis, who was made a Labour peer by Tony Blair in 2005, asked Lord Young whether he agreed this was "a clear and flagrant breach of the constitution".
"Can I ask him when the prime minister said Brexit was about taking control, did she mean the Conservative Party seizing control of the state in the interest of the Conservative Party alone?"
But, responding for the government, Lord Young said Mrs May had awarded only 21 life peerages since she came to power in July 2016, compared with 34 by Gordon Brown in his three years in office, 245 during David Cameron's six-year tenure and 374 during Tony Blair's decade in power.
Earlier this year, a review of the future of the Lords - which has 780 members - by crossbencher Lord Burns recommended a "two out, one in" approach to reduce the size of the chamber to 600 by 2027.
Lord Young said the government was "on track" to meet these ambitions given that 59 peers had either retired or passed away since the prime minister took office.
"There is no constitutional concept that there has to be some degree of parity between the main opposition and government parties," he said.
"The PM has show commendable restraint. It is the smallest dissolution honours list since 1979.
"My party got 42% of the vote (in 2017). We have 31% of the membership of the house. Compared with some other parties, I would maintain my party is still under-represented in my lordship's house".
Lib Dem peer Lord Newby called for a "firmer commitment" from ministers to the principles of the Burns report to show the way to other parties.
But Lord Young joked that if representation was based on votes at last year's election, in which the Lib Dems got a 7% share of the vote, as many as 60 Lib Dem peers might have to stand down.